1. Field of the Invention
This invention relates to the field of consumer electronics, and, in particular, to screening techniques for copy-protected material.
2. Description of the Related Art
Digital recordings have the unique property that copies of the content material have the same quality as the original. As such, the need for an effective copy-protection scheme is particularly crucial for the protection of content material that is digitally recorded. A number of protection schemes have been developed (or proposed) that record the content material in an encrypted form. Other protection schemes have been developed (or proposed) that record an encrypted key that controls the playback, or rendering, of the content material. In a number of these approaches, an attempt is made to minimize the value, or worth, of an illicit copy of copy-protected material by incorporating screens, or filters, in playback or recording devices that prevent the rendering or recording of these illicit copies. Because many alternative techniques are currently available, and because many other alternative techniques are being developed, the adoption of a single protection scheme by the providers of copy-protected material and the vendors of consumer electronic devices has been, and continues to be, a daunting task.
The Secure Digital Music Initiative (SDMI) has proposed a phased approach to enhanced methods of screening for illicit copies of copy-protected material. That is, because most security systems are embodied in programming code, it is relatively easy to upgrade a security system to effect alternative security measures as these measures are developed and standardized. Such an upgrade can be accomplished by sending a replacement memory device to a user, by having the user download the new programming code from an Internet site, and so on. Initially, for example, copy-protected material will contain an indication, or mark, that it is copy-protected material, or, in some cases, a mark that indicates that the material has been tampered with. For example, a mark may indicate that the content material has been converted to a compressed format when it should not have been compressed. A compliant player will not play content material that contains such a mark but does not contain the appropriate SDMI authorization. For ease of reference, content material that does not contain the appropriate SDMI authorization for the content material is termed Non-SDMI, or NSDMI. Also, for ease of understanding, the SDMI approach is used herein as a paradigm for security systems that utilize a phased approach to protection schemes.
A conventional SDMI screening process 100 is illustrated in FIG. 1. User material 101 is received by the process 100, and tested to determine whether it is material that has an appropriate SDMI authorization. If so, the SDMI material is provided to the processing components of the player or recorder, labeled “SDMI Functions” 120, in FIG. 1. These SDMI functions 120 process the material and provide the intended output 121 associated with the device; that is, a player renders the material via acoustic devices, a recorder records the material, typically in a secure form, on another medium, such as a recordable CD, and the like.
If, at 110, the material 101 does not contain the appropriate SDMI authorization, it is screened for a mark, at 130. If the material 101 does not contain the aforementioned mark, it is deemed not to be copy-protected material, and, therefore, freely playable or recordable. For example, copy-protected material may be marked using a “watermark” that cannot be removed from the material without destroying, or significantly degrading, the quality of the material. If a watermark is not detected at 130, it is likely that the user material 101 is not copy-protected. Such material may be commercial material that has been provided before the use of a watermark is adopted, or material, such as, private recordings or other recordings, that are intentionally not copy-protected. If, at 130, a mark is not found, the material 101 is processed, at 170, to be SDMI-compatible, for subsequent rendering or other processing, via the SDMI functions 120. Other security tests, such as commonly used existing copy-protection tests, may also be applied in block 130 to determine the validity of the user material 101. Similarly, the SDMI functions 120 may also include further protection-providing functions that are used to determine whether the output 121 is provided.
If, at 140, the material 101 is determined to be illicit, or potentially illicit, the state of the process 100 is assessed to determine whether it contains phase II security screens. That is, the aforementioned security mark will contain an indication that phase II security screens are available. When illicit copies of the content material containing this mark are made, they will also contain the mark. Thus, when the user of the illicit copy attempts to play or record from this illicit copy, the test at 140 will detect this indication, and will advise the user, at 150, that there's a problem rendering the user material 101, and will further advise the user that an upgrade is available for the user's system. When the user upgrades the user's system in response to this advice, advanced screening techniques are provided, as illustrated by block 160. That is, when the user upgrades to the Phase II system, the block 160 is provided or upgraded, via a memory device upgrade, a download from an Internet site, and so on. Other blocks, such as the SDMI functions block 120, the mark detection block 130, and the pre-processing block 170 may also be enhanced or modified by the upgrade. Thereafter, subsequent attempts to render or otherwise process illicit material will be subject to these enhanced security techniques. It is expected, for example, that one of the enhanced techniques will be a trace of the source of illicit material. That is, for example, future recording or providing systems may add a unique identifier to each provided material, identifying itself; for example, material downloaded from a web-site may contain that web-site name. When such material is determined to be illicit, the block 160 may provide a message such as: “This material has been illicitly obtained from site xxx.com, and the performers are being deprived of their royalty rights. Please refrain from purchasing material from xxx.com.” In this manner, the unintentional purchaser of illicit material is advised of the nature of the product he or she is receiving from the identified site, and will seek another source for the desired material. Eventually, the identified providers of illicit material will lose their customer base to the authorized providers, and the economic infeasibility of providing such illicit material to a dwindling customer base will force the illicit operation to shut down. Also, advanced systems may be configured to communicate this information to a central authority, so that preventive measures may be taken to prevent future losses.